The invention relates to a high-performance light-section wire mill including a break-down train with a plurality of roll stands or roll units, at least one intermediate mill, and, located downstream of the intermediate mill, a finishing train or finishing block for single-wire or multi-wire rolling of a wire or rolling stock having a circular cross-section and made of a high-grade steel.
Modern high-performance wire mills comprise at most one break-down train located downstream of a heating installation, one or several intermediate mills, and a finishing block for the rolling stock. The roll stands in the break-down train and the intermediate mills are robustly build and are designed to meet high requirements of a rolling mill. They are driven separately, with pilot and main drives, which are arranged in a housing with a minimum use of space. The rolling stock guides, in order to achieve high-quality outer surfaces, are formed as roller guides. The rolling stress, in the break-down train, is effected by stressing the roll sets with a pushout device and, in the intermediate mill-by replacing the whole stand by a crane. In order to reduce the rolling stock tolerances and to increase the operational reliability as well as the throughput, there are provided in the intermediate mill advantageously compact stands with a horizontal/vertical arrangement of the rolls. These stands with their flying roll shafts permit use of high wear-resistant roll materials for achieving long pass stay times.
A finishing block is a rolling apparatus that consists of several, primarily, from six to ten roll units, which are alternatively arranged at an angle of 90.degree. to each other. These roll units are closely arranged one after another along a pitch line in a common casing and are driven together from a single drive through a transfer gear box with two longitudinal shafts. Due to discontinuance of spindles, despite high rotational speeds, vibration of the drive parts is prevented. This is, among others, an important precondition for maintaining narrow tolerances. Separate roll units are arranged at most at an angle of 45.degree. and are equipped with flying rolls. The rolls have a relatively small diameter and are made of a high-grade steel or carry hard metal ring bands, e.g., from tungsten carbide, for increasing the pass stay time. This means that the pass does not change its form and stays for a long time.
Putting the ring on and off is effected by means of a hydraulic device within several minutes. Modern finishing blocks operate with a rolling speed up to 100 m/sec. or more. This is an important precondition for efficient and continuous operation of a roll mill.
After the finishing block, there is arranged a water-cooling section with integrated equalizing means. Dependent on the size and the quality of the rolling stock, the cooling section is regulated in such a manner that, even at the maximal rolling speed, a desired temperature profile in the rolling stock is achieved. After the water-cooling section, the rolling stock is air-cooled, e.g., in a Stelmor installation. At the end of the Stelmor installation, there is provided an adjustable drop stage connected with a chain conveyor. The chain conveyor transports wire loops to a coil-forming chamber. The coils are then placed on a hook conveyor at an up-ender discharge station and are transported to a binding installation and then are shipped away.
When, e.g., in the above-descried mill train, the total pass reduction is increased resulting in either larger billet size or in a reduced size of the finished product, the technological limits of the mechanism of the basic design become quickly visible. With a plurality of installations, the object of increasing the throughput and improving the rolling stock quality up to now, as a rule, was achieved by replacing the whole parts of the installation with the most modern ones. This necessitated substantially increased investments from the involved enterprises. Many existing roll mills can be modernized so that the installation will permanently operate with the highest possible speeds. However, high rolling speeds put high demands to the precision of all parts of the installation, e.g., they require increased reaction times of hydraulic and pneumatic devices and of other mechanical devices as, e.g., of chop shears, from which a very high precision of the switching time is required. The high speed in the finishing block necessitates an extremely high rotational speed of the roller guides. This can result in damage of the bearings. Also, the bearing of the drive shafts in the finishing block are stressed to a very high degree.
Accordingly, the object of the invention is a high-efficient light-section wire mill which, if necessary, can operate in the technical fringe range, with little increase in use of additional mechanical and technical devices and in untenable investment expenses, and which insures increase in throughput and in the final rolling speed as well as improvement of the texture and the tolerances of the rolling stock.